Elements of progressive rock

Progressive rock is a subgenre of rock that was at its peak in the 1960’s and 1970’s. Largely a British rock movement, it attempted to bridge the gap in between rock, jazz, and other genres of music. It came out of the psychedelic rock subgenre and still has some characteristics of it, including the “attempts to replicate and enhance the mind-altering experiences of psychedelic drugs”. It includes several of my favorite bands, some of which are Genesis, Pink Floyd, and Emerson, Lake, and Palmer. These bands tend to alter the generic form of verse, chorus, bridge and like to lengthen out these sections or performing long interludes in between them. With the blending of jazz into the mix, the usual 4/4 time signature of most rock genres is cast aside for a different one. The songs tend to feeling long and flowing with a freer rhythmic approach. Melodies tend to be modal with a long build up instead of fast paced. Other sounds are likely to be in songs as well, used as imagery for concepts. For example, Pink Floyd uses clock sounds and cash registers in the Dark Side of the Moon album, while Emerson, Lake, and Palmer uses a lot of synthesizers in their songs.
Listening guide:

This song is called Romeo and Juliet by Emerson, Lake, and Palmer. It features a heavy emphasis on synthesizer sounds. The title, an allusion to the tragic story of two people killing themselves out of love, also gives reasoning behind the kind of eerie, dark sound of this song.
0:14 This slow intro builds up until the melody starts here.
0:55 Bridge with orchestral instrument sounds
1:21 Guitar solo. Lots of recurring notes, with a bit of the melody mixed in.
1:43 Goes back to the melody from the beginning of the song
2:08 Sounds like the song is done, then they start up the
2:15 Solo on electric keyboards that builds up until the song is done